I'm the author of the high performance multithreaded sparse matrix library `librsb' (mostly C, LGPLv3): http://librsb.sourceforge.net/
I'm *not* a user of SciPy/NumPy/Python, but using Cython I have written a proof-of-concept interface to librsb, named `PyRSB': https://github.com/michelemartone/pyrsb
PyRSB is in a prototypal state; e.g. still lacks good error handling. Its interface is trivial, as it mimicks that of SciPy's 'csr_matrix'. Advantages over csr_matrix are in fast multithreaded multiplication of huge sparse matrices. Intended application area is iterative solution of linear systems; particularly fast if with symmetric matrices and many rhs.
With this email I am looking for prospective: - users/testers - developers (any interest to collaborate/adopt/include the project?)
Looking forward for your feedback, Michele